Conventionally, there is known a liquid crystal display apparatus which can display an image on a liquid crystal panel. At present, the main type of the liquid crystal apparatuses displays a color picture by illuminating a transmissive liquid crystal display panel having a color filter from the backside of the transmissive liquid crystal display panel. Although cold cathode fluorescent lamps (CCFL) using fluorescent tubes have been largely used for backlights, use of mercury is being limited now because of environmental concerns. Therefore, light emitting diodes (LED) have begun to be used as light sources instead of CCFLs containing mercury (for example, see Patent Document 1).
Further, the backlight devices are roughly classified into two types, i.e. a direct type and an edge type depending on arrangement of light sources. The direct type is formed by arranging a light source on an immediate back side of a liquid crystal panel as illustrated in FIG. 2(a). The edge type is formed by arranging a light guide plate on an immediate back side of a liquid crystal panel and arranging a light source on a side surface of the light guide plate as illustrated in FIG. 2(b). The edge type backlight-system illustrated in FIG. 2(b) has been used for liquid crystal panels having a relatively small size used for, for example, mobile phones and notebook-sized personal computers. However, because it is impossible to obtain a sufficient luminance for a large-sized liquid crystal panel when the edge type backlight-system is applied, a direct type backlight device may be used.
In the direct type backlight device using the light emitting diodes as the light source, there are a system of using white light emitting diodes as the light source and a system of obtaining white light by mixing colors from the light emitting diodes emitting red light, green light and blue light as illustrated in FIG. 3(a).
There is a method of emitting white light using light emitting diodes emitting three primary colors of red light, green light and blue light, the method employing a unit including two green light emitting diodes having the highest visibility for luminance, one red light emitting diode and one blue light emitting diode as illustrated in FIG. 3(b). With this structure, a color mixing performance for obtaining white color is enhanced, color unevenness and luminance unevenness are restricted, and power consumption is reduced (see, for example, Patent Document 2).    [Patent Document 1]    Japanese Laid-open Patent Publication No. 7-191311    [Patent Document 2]    Japanese Laid-open Patent Publication No. 2006-133721